Add creation of a log with last indexing informations. GNP-6338

The script logs indexing related actions, only when LOGIN variable is set, hence the updated documentation related to SSH SetEnv: https://forgemia.inra.fr/urgi-is/team-documentation/-/wikis/Connexion-%C3%A0-distance-et-connexion-aux-machines-virtuelles/diff?version_id=958057c3ad2af677c6ad1cc20bb5f1ebf51fccec